Flushing Meadows, NY -- (Sports Network) - French Open and Olympic runner-up Dinara Safina was an easy fourth-round winner Monday at the 2008 U.S. Open.

The sixth-seeded Safina handled German Anna-Lena Groenefeld 7-5, 6-0 on Labor Day at the USTA Billie Jean King National Tennis Center. The red-hot Russian advanced in 1 hour, 15 minutes with the help of five aces and six service breaks, compared to only two breaks for Groenefeld.

Safina reached the finals in six of her previous seven tournaments, including three titles, heading to New York, where she was a quarterfinalist two years ago.

The 22-year-old Safina, the younger sister of men's two-time major champion Marat Safin, lost to current world No. 1 Ana Ivanovic in the French Open finale back in June and gave way to fellow Russian Elena Dementieva in last month's gold-medal match in Beijing.

Safina's quarterfinal opponent will be 16th-seeded Italian Flavia Pennetta, who cruised past 32nd-seeded Frenchwoman Amelie Mauresmo 6-3, 6-0. Pennetta handled Mauresmo in 1 hour, 23 minutes, with the help of a whopping 14 double faults by the Frenchwoman. Mauresmo had her fragile serve broken no less than seven times.

The fading Mauresmo is a former world No. 1 and two-time major champion.

The 26-year-old Pennetta, a two-time titlist on the WTA Tour this season, will now appear in her first-ever Grand Slam quarterfinal.